Can i use 6mm cable for my 9.5 kw redring electrical shower?

The cable is already fitted but i want to upgrade to 9.5kw using a 45 amp type b circuit breaker . Most of the cable run is clipped direct ie ran up an inside cuboard and then into the loft before being enclosed for the last few meters . I am dis-agreeing with my dad because according to the regs clipped direct rate 6mm at 46 amp but enclosed is 36 amps who is right .(by regs i think the cable should be 10mm )

thanks for answer jim . I considered the cable run ,its less than 15meters .threfore the cable volt drop is small .

alan.turner5@btinternet.com, March 2007

if in doubt always over engineer. 10mm will be sufficient. As for the different rating, it's to do with heat loss from the cable. Remember to have included the uprating of the cable if it passes through more than 50mm of insulation. sounds daft, i know, but thats the regs.

jim, April 2007